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  <script>
    // const str = 'pink'
    // console.log(str.length)
    // const num = 12
    // console.log(num.toFixed(2))
    // const str = 'pink'
    // js 底层完成， 把简单数据类型包装为了引用数据类型
    // const str = new String('pink')
  </script>
</body>

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